Evolution, ecology and genomics of the Great Lakes invader, the red algal species Bangia atropurpurea.

红藻（Rhodophyta）是一个古老的谱系，可追溯到1.2和1.7 Ga；这两种化石都推迟了真核生物的多细胞进化和有性生殖的进化。此外，红藻是地球上光合作用生命进化的关键群体，含有初级叶绿体，并通过次级和三级内共生为其他真核生物谱系提供叶绿体。尽管这一群体的重要性显而易见，但对许多红藻谱系，特别是门中更基础的分类，仍然知之甚少。直到最近，基因组测序才被用于检查这一门的成员，并注意到红藻和其他真核生物之间的差异，以及独特的耐受性。在这个提议中，我们的目标是测序的基因组和选择的转录组的物种孟加拉atropurpurea。这项研究计划将是第一个对一种严格意义上的淡水红藻进行基因组测序的研究，这种红藻也是劳伦森五大湖的一种入侵者。值得注意的是，Bangia是红藻中唯一一个只在淡水（非咸淡水）中有一个物种而在海洋环境中有其他物种的属，它是唯一一个实验证明从海洋到淡水或反之亦然的红藻。因此，该属是一种很好的模式生物，用于研究由于渗透胁迫引起的转录组变化，我们将能够识别参与驯化和渗透胁迫过程的基因，并预测控制入侵新栖息地的限制。此外，1.2 Ga红藻化石在形态上与Bangia难以区分，因此是最古老的真核生物化石。该化石为真核生物有性生殖的化石记录提供了第一个证据，因此，该属是研究生命史不同阶段有性生殖进化和基因表达的理想物种。众所周知，孟加拉虎只进行无性繁殖，这种特殊的繁殖模式使其成为新栖息地的有效入侵者。

The red algae (Rhodophyta) are an ancient lineage in the fossil record dating 1.2 and 1.7 Ga; both of these fossils have pushed back the evolution of multicellularity in eukaryotes and the evolution of sexual reproduction. Furthermore, the red algae are a critical group in the evolution of photosynthetic life on earth containing primary chloroplasts and have also contributed chloroplasts through secondary and tertiary endosymbiosis to other eukaryotic lineages. Despite the obvious importance of this group, little is still known about many red algal lineages, in particular, the more basal classes within the phylum. Only recently, has genomic sequencing been used to examine members of this phylum and have noted differences among the red algae and other eukaryotes, as well as unique stress tolerances. In this proposal, we aim to sequence the genome and selected transcriptomes of the species Bangia atropurpurea. This research proposal would be the first to sequence the genome of a strictly freshwater red algal species, and this species is also an invader in the Laurentian Great Lakes. It is important to note that Bangia is the only genus in the red algae to have a species solely in freshwater (not brackish) and others in the marine environment and it is the only red alga to have been shown to experimentally transition from marine to freshwater or vice versa. Hence, this genus is an excellent model organism to examine transcriptomic changes due to osmotic stress and we will be able to identify genes that are involved in the process of acclimation and osmotic stress and predict the limits that control invasion into new habitats. In addition, the 1.2 Ga red algal fossil is morphologically indistinguishable from Bangia and hence is the oldest taxonomically resolved eukaryote fossil. This fossil provided the first evidence for sexual reproduction in the fossil record for eukaryotes and as a result, this genus is ideal to study the evolution of sexual reproduction as well as the expression of genes in different stages of the life history. Bangia atropurpurea is known to only reproduce asexually, and this particulary mode of reproduction enables it to be an effective invader into new habitats.